Its forecast track would take the storm toward Portugal but Vince was expected to gradually weaken on Monday as it moved over cooler waters. The hurricane was mainly a hazard to shipping, the hurricane center said.

The 2005 Atlantic hurricane season has been one of the costliest and deadliest for the United States, and Vince's formation made 2005 the second-busiest season since records began 150 years ago.

There were 21 named storms in 1933 and 19 in 1995. An average season spawns around 10 tropical storms, of which six become hurricanes. Tropical storms become hurricanes when their maximum sustained winds reach 74 mph (119 kph).

US hurricane researchers say the Atlantic has swung back into a period of increased storm activity that could last another 20 years. Some climatologists also believe global warming may be increasing the average strength of tropical cyclones.

Hurricane Katrina killed more than 1,100 people in Louisiana and Mississippi after coming ashore on the US Gulf Coast on Aug. 29 and flooding New Orleans.

The Gulf Coast was also struck this season by hurricanes Dennis and Rita while the Mexican tourist resort of Cancun was battered by Hurricane Emily.

Hurricane Stan in the past week has killed around 1,800 people in Central America after heavy rains caused mudslides that buried entire villages.